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Sepura Models and Simulates Complete Physical Layer for Professional Mobile Radio with Simulink

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Sepura SRH3500 SGPS™ hand-held radio

"We developed a complete model of the TETRA physical layer using Simulink. As the core of our development efforts, this model enables us to test out new ideas, analyze problems, and accelerate the pace of development."

Martin Popple, Sepura

Around the world, police, fire, ambulance, military, and other public safety organizations that depend on mobile communications in emergencies use TErrestrial Trunked RAdio (TETRA) equipment. Released in 1995 as a European Telecommunications Standards Institute (ETSI) standard, TETRA is noted for its security, reliability, short call-set-up times, and range.

As an industry leader in TETRA technology and radios, Sepura Ltd. supplies more than 600 organizations in more than 80 countries. Using Simulink and other MathWorks tools, Sepura built a complete model of the TETRA physical layer, which they use to develop TETRA radio technology and products, as well as to support TETRA Release 2 ETSI standardization.

"The Simulink model of the TETRA physical layer is central to our development efforts," says Martin Popple, Senior Software Engineer at Sepura. "We use it to rapidly test our algorithms in a simulation environment. This approach lets us try new ideas and identify problems early on rather than delaying debugging and verification until the system is implemented in the hardware."

Challenge

To keep pace with market demands for TETRA technology, Sepura must respond rapidly to customer needs and play an active role in TETRA standards development. Sepura engineers needed a design and development environment that would enable them to simulate and verify new algorithms and propose standard changes before implementing them in hardware. The team also needed an efficient way to identify and diagnose performance problems.

In the past, Sepura engineers used disparate tools for simulation and data analysis, which added extra data formatting and translation steps each time they processed simulation results. The group wanted a single, integrated development environment for modeling, simulation, and post-processing.

Solution

Using Simulink, MATLAB, and companion products, Sepura engineers developed a complete model of the TETRA physical layer. The model provides a foundation for the design and development of new products, as well as for the analysis of proposed standards.

The engineers based the model on an existing set of C code libraries. They used Simulink S-functions to incorporate their C modules into the model as blocks.

Once they had built a complete model, they simulated the transmission and reception of data across a TETRA network. They used MATLAB to post-process the simulation results and verify the correct operation of the model.

Sepura engineers used this baseline model to diagnose anomalies and resolve problem reports. Engineers recorded burst data from actual hardware, imported the data into Simulink, simulated the burst decoding process, and analyzed the results in MATLAB. "With Simulink we could identify right away whether the problem was with the burst itself or with the decoding algorithms," says Dr. Popple. Sepura engineers used DSP System Toolbox and Communications System Toolbox to develop new algorithms for implementing TETRA's π/4 differential quadrature phase shift keying (π/4 DQPSK) modulation scheme. They used blocks for coding, interleaving, modulation, convolution, filtering, synchronization, decoding, and other operations.

After debugging the new algorithms in this reference model with Simulink, the team replaced blocks from DSP System Toolbox and Communications System Toolbox with S-functions written in C.

They compared simulation results from this model with results from the reference model to verify the C code, an approach that expedited the process of implementing the system on Sepura's proprietary hardware.

Sepura is currently using the physical layer model and Simulink to support the ETSI TETRA Release 2 standardization process by verifying proposed standards through simulation.

Since 2003, SEPURA has used MATLAB and Simulink in the development of its leading handset products, including the SRH3000 family.

Results

  • Accelerated development. "A fundamental benefit of Simulink is the ability to evaluate our new algorithms in reference models with ease," says Dr. Popple. "Working in Simulink instead of in hardware enables us to move development forward quickly. Having direct access to the resultant simulation data for post-analysis and visualization in MATLAB is another great advantage."
  • Precise diagnostics. In the Simulink environment, we can compare real-world results with reference time series generated by simulations of the receiver chain and find out exactly what’s going on," Dr. Popple explains. "By moving our hardware problem into the Simulink environment, we immediately find out exactly where the problems are, and that saves an enormous amount of time."
  • Verified standards. "Sepura plays a leading role in the ETSI TETRA Release 2 standards process," says Dr. Popple. "We use MathWorks tools to help ensure that new standards are defined appropriately by verifying bit-error-rate measurements and other aspects of the physical layer."

Challenge

To accelerate the development of TETRA-based mobile communication technology

Solution

Use MathWorks tools to build, simulate, and verify a complete model of the TETRA physical layer

Results

  • Accelerated development
  • Precise diagnostics
  • Verified standards

Products Used

Learn more about Sepura